The present invention relates to a method for the entrapment and minimization of hazardous moisture bearing waste material, and more specifically, to a method for entrapping the hazardous components of moisture bearing low-level radioactive and mixed waste material and substantially reducing the volume of hazardous aqueous radioactive and mixed waste material.
Various types of sorbent material are used for spill control and in the packaging of liquids, sludges, and other moisture-bearing low-level radioactive and mixed waste material. Mixed waste material is defined as waste containing both radioactive and hazardous components as defined by the Atomic Energy Act (ATEA) and the Resource Conservation and Recovery Act (RCRA). Low level waste is generally defined as waste that contains radioactivity and is not classified as high-level waste, transuranic waste ("TRU"), or spent nuclear fuel. The choice of acceptable sorbent material depends upon the characteristics and the manner of disposing of the waste material. Sorbents, such as loose clay chips, mineral silica, vermiculite, and diatomaceous earth have been used in the industry for a long time. Although relatively inexpensive, some mineral type sorbents absorb only 10 to 15 percent by weight. Many mineral sorbents are very heavy and considerably increase the volume of solid waste which must be stored or buried at designated sites that are rapidly being filled by the ever increasing volume of waste material generated each year. Other sorbents, such as vermiculite, are highly absorbent but much more compressible, making it unsuitable when compression loads must be considered. Moreover, the use of mineral sorbents is labor intensive and often creates dust problems which enhance the risk associated with handling hazardous waste materials. Cellulose and wood based sorbents, such as cotton fiber, sawdust, wood pulp, corn cob centers and other biodegradable materials, are very combustible and are suitable where the primary means of disposal is incineration. However, biodegradable sorbents may be banned from hazardous based landfills because of the potential release of dangerous chemicals to the environment.
One of the most promising materials available today for aqueous based moisture bearing wastes are the polymer sorbents known as polyacrylates. Polyacrylate sorbents are non-biodegradable, lightweight, low volume, and are incinerable. Polyacrylates are generally available in granulated or powder forms which are activated by the water in the waste material. The polyacrylates chemically bind the liquids to the polymer molecules to form new molecules as a matrix which can hold the liquid in a very stable gel-like matrix at significantly higher pressures. Polyacrylates have a very high liquid to sorbent ratio, often up to a 200 to 1 ratio. Some polyacrylates react with remarkable speed to encapsulate and retain the hazardous component of the waste material within the matrix. However, until now, no effective devices or systems have been developed which offer the benefits of polyacrylate sorbents for wide-spread use in hazardous waste clean-up and disposal operations, and particularly for radioactive waste entrapment and minimization.
In view of the foregoing, a need exists for a device and system for delivering polyacrylate sorbent material to hazardous waste spills and leaks so that the waste is contained quickly and safely. A further need exists for a system of treating contaminated soil and other moisture bearing waste material which significantly reduces the moisture content and provides a solid waste material having no free standing liquids. A need also exists for a system which stabilizes large volumes of aqueous radioactive waste material and substantially reduces the volume of the waste material to be buried or stored at waste disposal sites.